Purification of succinic acid and succinic anhydride



Patented Oct. 3, 1933 Q g t PURIFICATION OF SUCCINIC ACID AND SUCCINIC ANHYDRIDE Alphons 0. Jaeger and Franz P. Fiedler, Mount Lebanon, Pa., assignors to Selden Company, Pittsburgh, Pa., a corporation of Delaware No Drawing. Application March 23', 1932 7 Serial No. 600,818' f 19 Claims. (Cl. 260-122) This invention relates to the purification oi obtainable in the trade under thename' or, crude or semi-purified succinic acid and anhyalumina gel, but any of the other catalytic ad dride and particularly crude products obtained sorbents described in the application of A. 0. from the reduction of crude maleic or fumaric Jaeger, Serial No. 337,534, filed February 4, 19 29 acids. which is now'Pate'nt No.- 1,852,782, issued- April 5,

Maleic and fumaric acids, which may be ob- 1932 may be used and are included. It is undertained by the catalytic oxidation of organic comstood, of course, that the use of catalytic adpounds such as benzene, toluene, iurfural, phesorbents in the purification of organic sublimable nols, wood tar, phthalic anhydride, etc. or as bymaterials generally is not claimed in the present lOiproducts from the catalytic oxidation of naphapplication, but, on the contrary, the use of a thalene or phenanthrene to phthalic anhydride catalytic adsorbent for removing'colored impuriand anthracene to anthraquinone are frequently ties is claimed only in combination with the'subobtained in a crude state, especially when they limation of succinic acid which forms the'primary are obtained as by-products from the leaching of subject matter of the present application.

l'5flow grade phthalic anhydride, and they nor- Steam, particularly superheated steam, has mally possess a reddish-brown color and contain many advantages as a carriervapor. It has high large amounts of impurities. When such crude heatcapacity and minimizes decomposition of maleic or iumaric acid is subjected to reduction, succinic acid to the point where it is substantially either electrolytic or by means of zinc or other absent. Steam is also a-cheap-carrier-vapor and '20; methods, crude succinic acid is obtained which is thereforepreferred, although the invention is in is reddish-brown in color and contains tarry mano sense limited to the use of steam, and'where terials. This product is very difficult to purify slightly lower yields are unobjectionable air preby'any recrystallization methods as the colored sents someeconomic advantages. When sublimimpurities adhere very strongly. ing with steam it is desirable to condense outthe 25. It has been considered in the past and is resuccinic acid at temperatures above 100 0550' so ported in the literature that succinic acid cannot that it is obtained in a dry form, or, if desired, of be distilled or sublimed without extensive decomcourse, the steam may be condensed as well, re'-" position. According to the present invention the sulting in a water solution of succinic acid from surprising discovery has been made that when which the latter can be recovered by concentra 30i vaporized at a temperature not too greatly above tion andcrystallization, if desired; 35 thejmelting point of the succinic acid, particu- The invention will be described in greater de'-" larly when vaporizing with an inert gas such as tail in connection with the followingfspecific nitrogen, carbon dioxide, hydrogen, or especially examples: I 5 e steam, succinic acid or in the case of gases other Example 351 than steam, a mixture of succinic acid and succinic anhydride can be readily obtained with only 50 parts of crude succinic acid, obtained by the insignificant losses through decomposition, and a. electrolytic reduction of crude maleicacid'liquor product of excellent purity is obtained. from the fumetowers of plants for'the catalytic Where large amounts of colored impurities are dat O of ap h t0 phthalic d i 40iprBSBnt, the product of a straight sublimation, are heated in a sublimer to a temperature of 95.

'eifective practically is the aluminum oxide gel of the crude material.

with or without a fractional condensation from 185495.0 The molten'mass is reddi$hfbrWn 5 i the gas stream, results in a product which is of a i 0 a Contains Considerable quantities 0f high chemical purity but is still somewhat colored tarry impurities Aslow'stleam of air 0 (18119011 as some of the colored impurities are somewhat d de 'p d through the Sublimer, the

45 volatile, and of course even traceslof colored impera ure f which' pr f r b y m in n,- puritiestoo small to be detectable by ordinary s t, and the air whichhasbecome charged with chemical analysis are sufiicient to impart considu ic a d Vapo s i pa s d thr ug fa um el. erable color to the product. In such cases the d is h Condensed in frfletional -1 use of catalytic adsorbents between the sublimer densers maintained at the "followi g tempera,

50, and the condenser result in the production of pure ur :-jfirs j n e t 1 Second. White material. The adsorbent can be regenercondenser a 8 0 0-; and, h d nd s r at ated by burning out the impurities, heating with 9- 7 Parts Of Pu White lslleeinieaeid' superheated steam, or any other manner. The containing some anhydride are obtained, the yield catalytic adsorbent which has proven to be most being 98% or better of the succinic acid content acts as an anti-combustion catalyst. For exam ple, compounds which are described'in' my co. pending application Serial 7, 1928.

Example 2 Crude or semi-purified succinicacid obtained oy the zinc dust reduction of maleic acid leached from low grade phthalic anhydride condensed from the vapors in the cold condensers of a fractional condensation system is heated in a sublimer toa temperature of about 225? Cr Water is given off and the anhydride is formed. After formation of the anhydride the temperature is raised to 237-243" C. and air blown over or through the liquid succinic anhydride, the air then being led to a fractional condenser where a.

beautiful white sublimate of succinic anhydride condenses out. Yields over 90% ofthe amount of succinic-acid originally present are obtained.

. Instead of using air, nitrogen, carbon dioxide, hydrogen or gases containing hydrogen, such as water gas, may be used as a carrier. In such cases it is normally desirable to recirculate the carrier gas after the sublimed; succinic anhydride is condensed out in the condenser.

. V Example 3 Crude succinic acid obtained as desired in Example l or Example 2 is heated in a sublimer to a temperature of about 220 ,C., and then superheated steam at approximately the same temperature is blown through. The superheated steam carrying v aporsof succinic acid are passedv through alumina ge if there are sufficient colfrom catalytic oxidation processes.

ored impurities to contaminate the final product, and then the succinic acid is condensed, the condensers being maintained-at 110-115" C. A pure white succinic acid is obtained and the yield is .almost theoretical, there being practically no decomposition. I u

The invention has been specifically described in conjunction with succinic acid produced from the reduction of impure maleic acid obtained This field is themost important one for the present invention since crude succinic acid can be obtained very cheaply from the extremely crude byeproduct maleic acidqobtainable from the catalytic oxidation of naphthalene .to phthalic anhydride and thepurification of this succinic acid is par.-

t icularly difilcult by ordinary means. However,- the present invention is in no sense limitedto the purification of crudesuccinic acid obtained by this method and is applicable to'any crude succinic acid containing impurities which are relatively non-volatile obtained by any means. Even in the cases of succinic acid which are sufficiently pure so that they can-be practically purified by recrystallization processes, the present invention permits the use of a cheaper sublimation process, although the saving and advantages practically obtained by the use of the present invention are not as great as in the case of crude succinic acidobtained' by the reduction of crude catalytic maleic acids which are of such anature that they No..291 ,143, filed July cannot be: economically purified by any other means.

What is claimed as new is:

l. Amethod of purifying impure succinic acid containing impurities which are relatively nonvolatile, which comprises vaporizing the acidat Y a temperature above its melting pointand below its boiling point into a carrier gas stream and condensing the product included in the group consisting of succinic acid, succinic anhydride,

,and 'mixtures of succinic acid and succinic anhydride from said carrier stream.

2. A method of purifying impure succinic acid containing impurities which are relativelynonvolatile, which comprises vaporizing the acid at a temperature above'its melting point and below its boiling point. into a carrier gas stream and condensing the product included in the group consisting of succinic acid, succinic anhydride,

and mixtures of succinic acid and succinic anhydridefrom said carrier stream in a series .of condensers maintained at progressively lower temperatures. i

, A method of purifying impure succinic acid which been obtained by the reductiongof impure maleic acid recovered from vapor phase catalytic oxidation processes, which comprises vaporizing the acid at a temperature above its melting point and below its boiling point into a carrier gas stream and condensing the product included in the group consisting of succinic acid, succinic anhydride, and mixtures of succinic acid and succinic anhydride from said carrier streamj 4. A method of purifying impure succinic acid which has been obtained by the reduction of impure maleic acid recovered from vapor phase catalytic oxidation processes,- which comprises vaporizing the acid at a temperature above its melting point and below its boiling point into a carrier'gas stream and condensing the product included in the group consis'ting'of succinic acid,.

succinic anhydride, and mixtures of succinic acid and succinic anhydride from said carrier stream in a series of condensers maintained at progressivelyl wertemperatures. U

.5. A method according to claim 1, in which the carrier gas is superheated steam and the condensation takes place at a temperature above 100C. j 6. A method according to claim 2, in which the carrier gas is superheated steam and the condensation takes place at a temperature above 100C. a U f I 7.,A method 'accordin'g'to claim 3,, in which the carrier gas is'superheated steam and the con-f densation takes place at atemperature above 100 C.

S. A method according to claim 4, which the carrier gas is superheated steam and the condensation takes place at a temperature above v 9. A method of purifying impure succinic acid containing adsorbable colored impurities, which comprises vaporizing the succinic acid at a tem-' perature above its melting point andflbelow its boiling point into a' carrier gas stream, passing the vapors through an adsorbent for colored impurities, and condensingthej product included in the group consisting of succinic acid, succinic anhydride, and mixtures of succinic acid and sue: cinic anhydride from the carrier gas stream.

10. A method of purifying impure succinic acid,

which has been ,obtainedby the reduction of impure maleic acid recovered from vapor phase catalytic oxidation processes, which comprises vaporizing the succinic acid at a temperature above its melting point and below its boiling point into a carrier gas stream, passing the vapors through an adsorbent for colored impurities, and condensing the product included in the group consisting of succinic acid, succinic anhydride, and mixtures of succinic acid and succinic anhydride from the carrier gas stream.

11. A method of purifying impure succinic acid containing adsorbable colored impurities, which comprises vaporizing the succinic acid at a temperature above its melting point and below its boiling point into a carrier gas stream, passing the vapors through an adsorbent aluminum oxide gel for colored impurities, and condensing the product included in the group consisting of suc cim'c acid, succinic anhydride, and mixtures of succinic acid and succinic anhydride from the carrier gas stream,

12. A method of purifying impure succinic acid which has been obtained by the reduction of impure maleic acid recovered from vapor phase catalytic oxidation processes, which comprises vaporizing the succinic acid at a temperature above its melting point and below its boiling point into a carrier gas stream, passing the vapors through an adsorbent aluminum oxide gel for colored impurities, and condensing the product included in the group consisting of succinic acid.

succinic anhydride, and mixtures of succinic acid and succinic anhydride from the carrier gas stream.

13. A method according to claim 9, in which.

the carrier gas is superheated steam and the condensation takes place at a temperature above 1'7. A method according to claim 3, in which the maleic acid is obtained from the tail gases of a catalytic phthalic anhydride plant.

18. A method according to claim 10 ,'in which the maleic acid is obtained from the tail gases of a catalytic phthalic anhydride plant.

19. A method according to claim 12, in which the maleic acid is obtained from the tail gases of a catalytic phthalic anhydride plant.

ALPHONS O. JAEGER. FRANZ P. FIEDLER. 

